Field of the Disclosure
This disclosure relates generally to image sensors, and in particular but not exclusively, relates to dual conversion gain for high dynamic range image sensors.
Background
Image sensors have become ubiquitous. They are widely used in digital still cameras, cellular phones, security cameras, as well as, medical, automobile, and other applications. The technology used to manufacture image sensors has continued to advance at a great pace. For example, the demands of higher resolution and lower power consumption have encouraged the further miniaturization and integration of these devices.
Image sensors may implement dual conversion gain to obtain high dynamic range images. The high dynamic range images may be obtained by reading from pixels under low gain, then high gain, and then combining the two readouts to render the high dynamic range image. However, the readout circuitry and memory storage structures needed to read out the high gain as well as the low gain pixel data from dual conversion gain image sensors has required circuitry requiring relatively large layouts that consume significant amounts of semiconductor die area. It would therefore be beneficial to reduce the amount of circuit components needed to read out the high gain and low gain pixel data from such dual conversion gain image sensors to reduce layout areas and semiconductor die sizes of readout circuits.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.